Ret. Col. Mohamed Khouna Ould Haidallah (Arabic: محمد خونا ولد هيداله) (born 1940) was the head of state of Mauritania (Chairman of the Military Committee for National Salvation, CMSN) from 4 January 1980 to 12 December 1984. He unsuccessfully ran for president in 2003 and again in 2007.

As head of CMSN
Haidallah's main achievement was to make peace with the Western Saharan Polisario Front, which had been fighting Mauritania since it annexed part of the former Spanish colony in 1975. The CMSN opted for complete withdrawal from the conflict, evacuating southern Rio de Oro (which had been annexed as Tiris El Gharbiya) and recognizing the Polisario as the representative of the Sahrawi people. This led to a crisis in relations with the country's until-then ally Morocco, which had similarly annexed the remainder of Western Sahara, with Haidallah's government facing an attempted coup, troop clashes and military tension.

Foreign policy
On the domestic front, his most notable policies were the institution of Islamic sharia law in 1980-83, [10] as well as several failed attempts to rebuild the political system shattered by the 1978 coup -- first as a multiparty system, and then, after the first coup attempt against him, as a one-party state. [11] [12] It was also during Haidallah's rule that slavery was formally abolished in Mauritania, although the practice continues at a diminished level still today. He made a statement announcing the abolition of slavery in July 1980, and this was followed by a legal decree in November 1981. Political opponents were treated harshly, with imprisonments [13] and those responsible for one of the failed coups against his government were executed.

Activities after losing power
Following a military coup against Taya in August 2005, an amnesty in early September freed Haidallah from his sentence, along with more than a hundred others sentenced for political offenses.